On Thu, 13 Aug 2015 14:52:36 -0500, Thane wrote:

It's a mixture of potassium hydroxide and potassium carbonate.

Check this article.

http://www.thenakedscientists.com/HT...stion/1000207/

That was an interesting article, which also said that it could be a
mixture of ammonium chloride and manganese dioxide in the comments.

It seems that lemon juice or vinnegar (ie weak acids) are the way to
clean it up chemically, based on that article.